The present invention generally relates to paper feeding arrangements and more particularly, to a paper sheet feeding arrangement for feeding copy paper sheets one sheet by one sheet from a paper sheet cassette in a copying apparatus.
Conventionally, as a paper sheet feeding arrangement of the above described type, there has been proposed an arrangement in which a paper sheet cassette having copy paper sheets stacked therein is detachably mounted on a paper feeding section, while a feed roller and a paper sheet separating roller rotating in a direction counter to a paper feeding direction of the feed roller are provided forwardly of a paper feeding roller so as to extend in parallel with each other and vertically in contact with each other. In such a paper sheet feeding arrangement in which the copy paper sheets are separated from each other at a position disposed slightly forwardly of the paper sheet cassette, a paper feeding cycle of one of the copy paper sheets to be separated is completed in a state where a leading edge of the separated copy paper sheet has been transported to a contact point between the feeding roller and the paper sheet separating roller or has been gripped between the feeding roller and the paper sheet separating roller. Accordingly, when the paper sheet cassette is pulled out of the paper feeding section for replenishment of the copy paper sheets or replacement of the copy paper sheets with those of another size, such a problem arises that the separated copy paper sheet remains in the paper feeding section undesirably. Namely, it is troublesome to remove the copy paper sheet remaining in the paper feeding section. Furthermore, in the case where the paper sheet cassette is mounted on the paper feeding section without removing the copy paper sheet remaining in the paper feeding section, jamming of the copy paper sheet remaining in the paper feeding section takes place. Thus, in the paper sheet feeding arrangement of this kind, the copy paper sheet having its leading edge projecting out of the paper sheet cassette is required to be returned into the paper sheet cassette at the time when the paper sheet cassette is pulled out of the paper feeding section.
Furthermore, there is shown in FIGS. 1 to 3, a known paper sheet feeding arrangement provided with a lever type paper sheet returning mechanism for returning the copy paper sheet into a paper sheet cassette 60 mounted on the paper feeding section. A lifting lever 65 is pivotally projected into the cassette 60 upwardly from a bottom portion of the cassette 60 so as to be pivoted about a support shaft 67. A paper sheet support plate 61 having the copy paper sheets placed thereon is upwardly urged, at its front end portion, by the lifting lever 65 such that the upper face of the uppermost one of the copy paper sheets placed on the support plate 61 is brought into pressing contact with a paper feeding roller 80. When the paper feeding roller 80 is driven so as to be rotated counterclockwise, the uppermost one of the copy paper sheets placed on the support plate 61 is transported in the rightward direction in FIG. 1 together with one or more copy paper sheets through friction therebetween. Namely, at this time, two or more copy paper sheets are transported simultaneously by the paper feeding roller 80.
Meanwhile, a feed roller 30 and a paper sheet separating roller 40 rotating in the direction counter to the paper feeding direction are rotatably provided in contact with each other at the position forwardly of the paper feeding roller 80 and are each driven for counterclockwise rotation thereof. Therefore, the uppermost one of the copy paper sheets transported by the paper feeding roller 80 is fed in the rightward direction in FIG. 1 through counterclockwise rotation of the feed roller 30 and is further transported to a transfer section of a photosensitive drum (not shown) by a pair of transport rollers 85. However, travel of the remaining copy paper sheets transported by the paper feeding roller 80 is prevented through counterclockwise rotation of the paper sheet separating roller 40 so as to be stopped at the paper sheet separating roller 40.
As shown in FIG. 2, the paper sheet returning mechanism includes a return lever 20 mounted on a rotatable shaft 21, an arm 22 secured to one end portion of the shaft 21, and an arm 23 secured to a rotatable shaft 24. The arm 22 is formed with an elongated opening 22a. The arms 22 and 23 are coupled with each other by driving a pin 23a into the arm 23 through the elongated opening 22a. Meanwhile, an ejector arm 25 provided, at its distal end, with a roller 26 is fixed to the shaft 24. The arms 23 and 25 are urged to rotate in the counterclockwise direction by a torsion spring 27 wound around the shaft 24.
A front face of the cassette 60 inserted into the paper feeding section is brought into contact with the roller 26. Thus, the cassette 60 is depressed rearwardly in the leftward direction in FIG. 2 by an urging force of the torsion spring 27. Consequently, since a claw portion 15a of a lock lever 15 is positively brought into engagement with a lock hole 62 of the cassette 60 as shown in FIG. 1, the cassette 60 is securely positioned.
Meanwhile, a mechanism for releasing upward urging of the lifting lever 65 for the paper sheet support plate 61 includes a release operating lever 70, a release lever 73 and a retainer lever 75. The release operating lever 70 is upwardly urged about a shaft 71 by a torsion spring 72. The release lever 73 is provided, at its distal end, with a roller 74 and is secured to the support shaft 67 of the lifting lever 65. The retainer lever 75 is mounted on a shaft 76 and is urged in the clockwise direction in FIG. 2 about the shaft 75. Namely, when the release operating lever 70 is depressed downwardly, the lifting lever 65 is downwardly pivoted about the support shaft 67 together with the release lever 73. Thus, the release lever 73 is locked through engagement of the roller 74 of the release lever 73 with a step portion 75a of the retainer lever 75. At the same time, since a lock release lever 16 is downwardly pivoted by the roller 66 of the lifting lever 65, the lock lever 15 is pivoted downwardly and thus, the claw portion 15a of the lock lever 15 is disengaged from the lock hole 62 of the cassette 60 such that the cassette 60 is unlocked. It is to be noted that the lock lever 15 and the lock release lever 16 are rotatably mounted on a shaft 17 and are urged upwardly by torsion springs 18 and 19, respectively as shown in FIG. 3.
When the cassette 60 is unlocked as described above, the cassette 60 is thrusted out slightly in the leftward direction in FIG. 2 by the ejector arm 25 which is urged to rotate about the shaft 24 in the counterclockwise direction by an urging force of the torsion spring 27. At this time, the arm 23 is pivoted counterclockwise and the arm 22 is pivoted clockwise relative to the counterclockwise rotation of the arm 23. Therefore, since the return lever 20 is pivoted clockwise about the shaft 21, the remaining copy paper sheets are returned into the cassette 60 by a distal end of the return lever 20. Here, the remaining copy paper sheets are those stopped by the paper sheet separating roller 40 with their front ends proceeding up to the position between the feed roller 30 and the paper sheet separating roller 40.
However, the above described lever type paper sheet returning mechanism of the known paper sheet feeding arrangement has such drawbacks that the remaining copy paper sheets stopped by the paper sheet separating roller 40 can be returned into the cassette 60 by the return lever 20 only in the case where the remaining copy paper sheets stopped by the paper sheet separating roller 40 are disposed within a travel stroke of the return lever 20 and that since the feed roller 30 and the paper sheet separating roller 40 are held in contact with each other, the remaining copy paper sheets stopped by the paper sheet separating roller 40 may be damaged when being gripped, at the front ends, between the feed roller 30 and the paper sheet separating roller 40.